fix: ensure apt-get update runs on container update (#663)

Because of Docker layering, `apt-get update` and `apt-get install`
need to be in the same RUN command

fixes #604

Author: james-ball-qualcomm

.devcontainer/Dockerfile

@@ -5,10 +5,11 @@ ENV DEBIAN_FRONTEND=noninteractive
 WORKDIR /workspace
 
 RUN export DEBIAN_FRONTEND=noninteractive
-RUN apt-get update
 
 # please keep pkgs sorted
-RUN apt-get install -y --no-install-recommends \
+RUN \
+  apt-get update && \
+  apt-get install -y --no-install-recommends --fix-missing \
     build-essential \
     bundler \
     clang-format \